iMac inconsistently receives iMessages and text messages

[NOTE: I have already applied all recommended solutions for syncing and forwarding that have been posted as of 2/26/26.]. MY PROBLEM: iMessages and text messages sent to my cell phone number always arrive on my iPad and my iPhone. However, iMessages and text messages sent to my cell phone number only sometimes arrive on my iMac (2021, running Tahoe 26.2), but sometimes do not arrive on my iMac at all. Even if I send the iMessage/text message to myself, it arrives on my iPad and iPhone, but may or may not arrive on my iMac. I have been through all of the recommended solutions for syncing devices as of 2/26/26. As far as I can tell, all Apple IDs are identical, all text forwarding is turned on, all other settings meet the recommendations. What would account for this spotty reception of iMessages/text messages on my iMac? How can I fix this? Thanks in advance for your help.